The present invention broadly relates to tubing systems and, more specifically, pertains to a new and improved construction of a discharge system as well as to a method of operating such a discharge system.
Generally speaking, the discharge system and method of the present invention are intended for at least one tubing run or system or conduit line in an apparatus for the selective transport of fluid volume quantities from a first vessel to a second vessel. The inventive discharge system for a tubing system in an apparatus for the selective transport of fluid quantities from a first vessel to a second vessel comprises an outlet or delivery nozzle arranged in an upper portion of the second vessel, a transport conduit leading from a lower portion of the first vessel to the nozzle, means for transporting a fluid contained in the first vessel through the transport conduit toward the second vessel, a collector vessel, means for drawing fluid into the collector vessel, a suction conduit arranged at the collector vessel for drawing and conducting fluid into the collector vessel and a valve arranged in the transport conduit or in the suction conduit.
It is known, for instance from the Swiss Pat. No. 545,989, to provide a transport conduit in an apparatus of the previously mentioned type which leads from a lower portion of a first vessel to a delivery nozzle arranged above a second vessel. Means are also known, for instance from the same document, which are suited for the transport of a fluid contained in the first vessel through the transport conduit to the second vessel.
It is also known, for instance from the European Patent Publication No. 2103-A1, to provide a collector vessel for flushing purposes as well as means for drawing fluid into the collector vessel, a suction conduit for the fluid arranged at the collector vessel and a valve arranged in the suction conduit for inhibiting or permitting flow through the suction conduit.
The apparatus and method of the present invention are especially intended to be applied to systems employed in particle analyzers for the serial or sequential analysis of blood samples or specimens. Such systems serve to transport specimens prepared in a first vessel into the second vessel where such specimens are tested or analysed. After testing, all vessels and conduits of the tubing system must be flushed and fully discharged in order to avoid dilution errors and the entrainment or carry-over of specimen matter.
Simply blowing out the conduits in a system, as disclosed in the aforementioned Swiss Pat. No. 545,989, does not lead to the desired result in modern, complex particle analyzers in which erythrozytes as well as thrombozytes and leucozytes are tested. For testing leucozytes, the blood samples or specimens are treated by a haemolysator which influences the surface tension of the fluid such that the specimens tend to form foam, bubbles and droplets when mixed and when the conduits are blown out with air, especially in the proximity of the outlet or delivery nozzle. The foam can only be flushed out of the vessels with difficulty. Alternating tests or measurements of erythrozytes, on the one hand, and thrombozytes or leucozytes, on the other hand, are thus hampered or the flushing and discharge of the conduits becomes very complex.
The flushing of the conduits with a flushing solution by means of an apparatus known from the aforementioned European Patent Publication No. 2103-A1 does make it possible to largely eliminate the carry-over of specimens and the influence of the haemolysator but leaves the conduits full. When discharging these conduits by blowing them out, bubbles and droplets still form, especially at the outlet or delivery nozzle: at the end of the blowing out process, when the pressure and the air velocity subside, the fluid retained on the walls of the conduits by surface tension forces slowly flows back to the delivery nozzle and a bubble forms and remains suspended on such delivery nozzle. A few alternating fluid and air segments also form in the conduit as well as some foam when such segments reach the delivery nozzle.